WebGL Model rendering without color

Question

I am trying to write a javascript program that abstracts the WebGL functions so that I can draw different models with different shaders. I have created a shader object, which I will eventually modify to take shader programs as arguments, and a model object. The problem I am having is that my model is currently being drawn on the screen, but it is showing up black, instead of having the intended phong shader applied. I am not sure if the error is in my javascript or in my shader program. I am just trying to figure out if objects being drawn completely black is a specific issue or if it could be a number of different things. Any help is appreciated. Sorry if this question is too vague.

This is my Shader object:

 function Shader(){
    this.program = createProgram(gl, document.getElementById('vertexShader').text,
                                 document.getElementById('fragmentShader').text);


    this.vertexPositionLocation = gl.getUniformLocation(this.program, 'vertexPosition');
    this.vertexNormalLocation = gl.getUniformLocation(this.program, 'vertexNormal')

    gl.enableVertexAttribArray(this.vertexNormalLocation);
    gl.enableVertexAttribArray(this.vertexNormalLocation);

    this.projectionMatrixLocation = gl.getUniformLocation(this.program, 'projectionMatrix');
    this.viewMatrixLocation = gl.getUniformLocation(this.program, 'viewMatrix');
    this.modelMatrixLocation = gl.getUniformLocation(this.program, 'modelMatrix');

    this.lightPositionLocation = gl.getUniformLocation(this.program, 'lightPosition');

    this.lightColorLocation = gl.getUniformLocation(this.program, 'lightColor');
    this.modelColorLocation = gl.getUniformLocation(this.program, 'modelColor');



    gl.useProgram(this.program);

}

This is my Model Object:

function Model(model){
    this.positionArray = new Float32Array(flatten(model.positions));
    this.normalArray = new Float32Array(flatten(model.normals));
    this.triangleArray = new Uint16Array(flatten(model.triangles));

    //initialize buffer objects

    this.normalBuffer = gl.createBuffer();
    this.positionBuffer = gl.createBuffer();
    this.triangleBuffer = gl.createBuffer();

    gl.bindBuffer(gl.ARRAY_BUFFER, this.normalBuffer);
    gl.bufferData(gl.ARRAY_BUFFER, this.normalArray, gl.STATIC_DRAW);

    gl.bindBuffer(gl.ARRAY_BUFFER, this.positionBuffer);
    gl.bufferData(gl.ARRAY_BUFFER, this.positionArray, gl.STATIC_DRAW);

    gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, this.triangleBuffer);
    gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, this.triangleArray, gl.STATIC_DRAW);


    gl.enable(gl.DEPTH_TEST);

    Model.draw = function(shader){

        var modelMatrix = new Matrix4();
        var viewMatrix = new Matrix4();
        var projectionMatrix = new Matrix4();

        modelMatrix.rotate(modelRotationX, 1, 0, 0);
        modelMatrix.rotate(modelRotationY, 0, 1, 0);
        viewMatrix.translate(0, 0, -3);

        projectionMatrix.perspective(90, 1, 1, 10);

        gl.uniform3f(shader.lightColorLocation, 1.0, 1.0, 1.0);
        gl.uniform4f(shader.lightPositionLocation, 0.0, 8.0, 8.0, 1.0);    
        gl.uniform3f(shader.modelColorLocation, 0.6, 0.0, 0.0);


        gl.uniformMatrix4fv(shader.modelMatrixLocation, false, modelMatrix.elements);
        gl.uniformMatrix4fv(shader.viewMatrixLocation, false, viewMatrix.elements);
        gl.uniformMatrix4fv(shader.projectionMatrixLocation, false, projectionMatrix.elements);

        gl.bindBuffer(gl.ARRAY_BUFFER, normalBuffer);
        gl.vertexAttribPointer(shader.vertexNormalLocation, 3, gl.FLOAT, false, 0, 0);

        gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);
        gl.vertexAttribPointer(shader.vertexPositionLocation, 3, gl.FLOAT, false, 0, 0);


        gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, triangleBuffer);
        gl.drawElements(gl.TRIANGLES, triangleArray.length, gl.UNSIGNED_SHORT, 0);

}

}

Here's my fragment shader program:

    <script id = "fragmentShader" type="x-shader/x-fragment">
        precision mediump float;

        varying vec3 fragmentNormal;
        varying vec3 fragmentLight;
        varying vec3 fragmentView;

        uniform vec3 modelColor;
        uniform vec3 lightColor;


        void main() {

            vec3 n = normalize(fragmentNormal);
            vec3 l = normalize(fragmentLight);
            vec3 v = normalize(fragmentView);
            vec3 h = normalize(l + v);

            float d = max(dot(l, n), 0.0);
            float s = pow(max(dot(h, n), 0.0), 10.0);

            vec3 fragmentColor = modelColor * lightColor * d + lightColor * s;

            gl_FragColor = vec4(fragmentColor, 1.0);
        }
    </script>

Answer 1

So you see a silhouette of the model but it's black?

First thing I'd do is add

gl_FragColor = vec4(1,0,0,1);

At the bottom of the fragment shader. Does your model turn green? No? Then you're not using that shader.

othewise next I'd try

gl_FragColor = vec4(lightColor,1);

Does the model turn the color of the light? If no then you're setting the light color wrong

Next

gl_FragColor = vec4(modelColor,1);

Does the model turn the model color? If no you're setting the model color wrong.

Next I'd try

gl_FragColor = vec4(n * .5 + .5,1);

You should see your model's normals as colors. It's black then fragmentNormal is wrong.

Otherwise try the same with l , v , and h etc...